Azure web sites supports multiple web sites (and at the moment you can run several free websites in the Azure web sites preview).

When a new site is created it gets a default subdomain name in the “azurewebsites.net” domain, so if you create a web site called “mysite” then it would be available as “mysite.azurewebsites.net”.

It is also possible to configure custom domain names for the sites. To be able to use custom domain names the web site needs to be in the shared or reserved web site mode. Neither is free, you can see the current pricing information in the portal. (If you have an MSDN subscription or MPN association with benefits then you might get access to some resources as part of the subscription.)

If you have several Azure sites and want to map them to several sub-domains for your custom domain it is possible and quite easy. However, the documentation about this has improvement potential, hence this blog post.

Scenario:

A custom domain “stefanjohansson.org” needs to be mapped to 3 different sites in Azure:

domain name

Azure Site

Azure DNS name

stefanjohansson.org

myplainsite

myplaintestsite.azurewebsites.net

test1.stefanjohansson.org

my1sttestsite

my1sttestsite.azurewebsites.net

test2.stefanjohansson.org

my2ndtestsite

my2ndtestsite.azurewebsites.net

Custom CNAME records

Step 1 is to set up custom “awverify” CNAME mappings from each domain to Azure for verification so that Microsoft knows that you own/can administer the domain.

Name

Type

Data

awverify.stefanjohansson.org

CNAME

awverify.myplaintestsite.azurewebsites.net

awverify.test1.stefanjohansson.org

CNAME

awverify.my1sttestsite.azurewebsites.net

awverify.test2.stefanjohansson.org

CNAME

awverify.my2ndtestsite.azurewebsites.net

once the CNAME’s are valid and can be read by Azure you can create A-records for the subdomains so that you can reach Azure using the custom domain names

A Records

Step 2 is to configure A records for the domains and sub domains.

First look up the actual IP-address (faked as 10.10.10.10 below) of the sites in the manage domains page of the Azure management dashboard.

Configure Azure Websites

Step 3 is to configure the new A records in the Azure websites dashboard. The configuration tool checks that both CNAME and A records are valid so it is not possible to add this before the configuration changes in the DNS-system has propagated.

The manage domains link is in the Configure tab of the site in the bottom toolbar as below

Verification

Once the configuration is done the domain names should be visible in the Azure dashboard and you should be able to navigate to the custom domain name and be able to access your resources in the Azure web sites using your custom domain names.

Hi,
If you already have an A record for your sub domain you need to verify it points to the right IP. Once that is ok you need to configure the right Azure web site to answer the requests to that address.
Note that this post references how Azure was working in December 2012. A lot has happened since wrt Azure networking capabilities and possible setup scenarios.